Pattern-wise thermal transfer of materials from donor sheets to receptor substrates has been proposed for a wide variety of applications. For example, materials can be selectively thermally transferred to form elements useful in electronic displays and other devices. Specifically, selective thermal transfer of color filters, black matrix, spacers, polarizers, conductive layers, transistors, phosphors, and organic electroluminescent materials have all been proposed.
The present invention is directed to materials and methods for patterning an amorphous, non-polymeric, organic matrix with electrically active material disposed in the matrix, as well as the devices formed using the materials and methods. One embodiment of the invention includes a method of making an organic electroluminescent device. A transfer layer is solution coated on a donor substrate. The transfer layer includes an amorphous, non-polymeric, organic matrix with a light emitting material disposed in the matrix. The transfer layer is then selectively thermally transferred to a receptor. Thermal transfer can include laser thermal transfer or thermal head transfer.
Another embodiment is a donor sheet that includes a substrate and a transfer layer. The transfer layer includes a solution-coated, amorphous, non-polymeric, organic matrix with a light emitting material disposed in the matrix. This transfer layer is capable of being selectively thermally transferred from the donor sheet to a proximally located receptor. Optionally, the donor sheet also includes a light-to-heat conversion layer disposed on the substrate for converting incident imaging radiation into heat.
Yet another embodiment is a method of making a donor sheet. The method includes forming a transfer layer on a substrate by solution coating a coating composition on the substrate to form an amorphous, non-polymeric, organic matrix with a light emitting material disposed in the matrix. Optionally, the method also includes forming a light-to-heat conversion layer on the substrate.
Another embodiment is an electroluminescent device that includes a first electrode, a second electrode, and a light emitting layer disposed between the first and second electrodes. The light emitting layer includes an amorphous, non-polymeric organic matrix with a light emitting polymer disposed in the matrix. Such devices include, for example, single OEL devices for, for example, lighting applications and pixelated devices, such as displays, which contain multiple OEL devices.
It will be recognized that electrically active materials other than light emitting materials can be disposed in an amorphous, non-polymeric, organic matrix. For example, a conducting or semiconducting material can be disposed in the amorphous, non-polymeric, organic matrix. Application examples include the formation of a hole transport layer or electron transport layer or other charge conducting layer by disposing a hole transport material or electron transport material in an amorphous, non-polymeric, organic matrix. The matrix can be formed using, for example, any of the materials described above. This structure can be particularly useful for conducting or semiconducting polymeric materials to produce a layer with lower cohesive strength than the polymer itself.
In addition, these materials and methods can also be useful for non-thermal printing and transfer methods including, for example, inkjet printing, screen printing, and photolithographic patterning.